Life at the Center of the Universe

Caltech's Sean Carroll on space, time, God, death and being human

Sean Carroll spends his days pondering the origins of the universe and the nature of time. He then communicates his discoveries to the public in an effort to explain how the universe really works through a "scientific way of looking at the world," a method that has earned him celebrity status.

Carroll has written several books, including "From Eternity to Here" and "The Particle at the End of the Universe," and he's made appearances on Morgan Freeman's "Through the Wormhole" and "The Colbert Report." Recently, he consulted on an episode of "Bones," which premieres tomorrow night at 8 p.m. on FOX.

A theoretical physicist at Caltech since 2006 who just returned from giving lectures in London and Paris, the 47-year-old hails from Philadelphia and has lived in Boston, Chicago and Santa Barbara. He currently resides in Echo Park.

Two weeks ago, "The Particle at the End of the Universe," about discovering the Higgs boson particle, or as it's been called in the mainstream media, "The God Particle," was awarded London's Royal Society's Winton Prize for Science Books.

Most recently, Carroll introduced author Charles Yu at Red Hen Press' 19th anniversary luncheon at the Westin in Pasadena. In January, Carroll will be participating in the Veritas Forum debate on science and religion at Caltech. He's also preparing to serve as guest lecturer on a Scientific American-sponsored cruise through Hong Kong, Vietnam, Thailand and Singapore.

"It's kind of amazing that I get paid to do this," he said. "But it's kind of fun when you figure things out."

As busy as he is, Carroll recently sat down with the Pasadena Weekly for a brief discussion on the universe, space, time, God, life after death and the overall significance of human beings.

Pasadena Weekly: What is time?

Sean Carroll: The simplest way to say it is that time is a label on the universe, just like space is. We live in a world that is full of stuff that's moving around, changing as time passes, and time is just a label on all those different moments. What's difficult is not ‘What is time?' That's fairly straightforward. It's how time works that is difficult. Why are we all born young and then age and die? Why is it always in the same order? Why do we remember yesterday but never tomorrow? How does time work at the subatomic level with quantum mechanics and laws of physics we don't understand very well? How does it work at the birth of the universe? These are all good questions to which we don't know the answers. We know how it functions, in theories and in our everyday lives. Time is a parameter. It says that the universe happens over and over again, just like the frames of a film strip, and time is a label on which moment you're talking about at that moment. There's nothing special about the present moment. The laws of physics treat all moments of time equally. So it's tempting to say all moments of time are equally real. The danger is when people start saying, ‘Well are you saying all moments of time exist now?' That's an ill-formed sentence, because they exist but they don't exist now, now only this one moment exists. So you get into a philosophical question which is best thought of as not what is real but what is the best way to think about mapping our experience onto these theories we have of the universe.

In ‘From Eternity to Here,' you talk about how the Big Bang was the most orderly state and since then the universe has been getting more and more chaotic. How does that impact an individual's life?

As an individual you don't need to know that the Big Bang was low entropy or orderly. However, the fact that it was orderly is absolutely central to your life. It absolutely determines everything about how time works in our present universe, because the fact that the universe was low entropy and orderly to begin with means that it will over time become more disorderly and ultimately it will be as disorderly as it can get. We're nowhere near that now. It's going to take something like 10100 years, and the universe has only been around for 13 billion years. So we are in the middle of this process that the universe is going through of becoming more and more disorderly, and in fact we are a spin-off of that process. We can only exist because the sun provides us energy in a very useful, low entropy form, and then we use it up and give it back to the universe in a useless, high entropy form. So we're sort of parasites living off the fact that the universe is increasing in entropy.

What do you think is the path of the universe? Will it expand forever, contract forever? Is it part of a multiverse or is it something else?

I don't think that the universe will be cyclic. I don't think it will expand and contract in some infinite pattern. I tend to guess that it will expand forever. But we're not exactly sure what the future holds, or the past for that matter. There are good reasons to believe that we are part of a bigger multiverse, but that's certainly not anywhere near established. The leading theory of the universe is that it will expand forever. Currently we know that our universe is not only expanding but accelerating because of something called dark energy. It's very possible, plausible, even likely that that will just continue for all time. If that's true, then the stars are burning their fuel right now and giving off light but they only have a finite amount of fuel, so eventually they will die out. They will fall into black holes, but those black holes are going to radiate away. Stephen Hawking told us that even black holes are not forever, they eventually evaporate into the world around them. And then it's just empty space, forever and ever and ever. Cold and dark and lonely and not a hospitable universe. Take that into account when you do your life insurance policies, right?

How did something come from nothing?

We don't know, but we know that it's not impossible by any stretch. It's not as if there's some logical obstacle that prevents us from understanding that. There're two obvious possibilities and we don't know which, if either, one of them is right. One is that there was truly a beginning to the universe, which means there was a moment before which there was no space and time, before which there weren't any moments. In that case it seems bizarre to us because we think of what happens now being caused by what happened before. In this theory, where the universe had a beginning, that wouldn't be true because there was no before. But that's just because we live in a very tiny part of the universe and we're used to things being caused and so forth. The bigger question for cosmology would be is there a sensible theory of the universe in which there was a first moment of time? And the answer is sure, there could very well be. We don't know yet whether it's true. The other possibility is that the universe is eternal, that it just goes back forever and ever. We had a Big Bang 13.8 billion years ago but we don't know whether that was truly a beginning or whether it was just a phase the universe went through. So it's absolutely possible and in fact my favorite idea is that there was a universe before the Big Bang and we just need to learn how to extrapolate our theories that far.

Is God incompatible with what we know about science?

There are different varieties of God, so it's hard to say what one's stance on God is until you choose what god you're talking about. Science doesn't disprove God or anything else. It doesn't disprove the idea that the reason why the moon goes around the earth is because angels are pushing it. There's no need for that idea. We have a perfectly good theory of gravity that does perfectly well at explaining why the moon goes around the earth. That's the attitude most cosmologists and physicists have toward the universe. We can't disprove the idea that God created the universe or sustained it, but we have absolutely no need for that idea either. So it's true some scientists are quite religious, but it's a much smaller fraction of scientists than of nonscientists who are religious.

Why do you think people have been so receptive to your work?

Like Woody Allen said, 90 percent of success is just showing up. I actually enjoy and make an effort to spread the word, to talk to broad audiences, to write on my blog, writing books and things like that. It's very important because the kind of science that I do is not about curing cancer or building a better transistor. There are essentially no practical implications for what I do, but it's valuable because we are a curious species. It's very important that we share with the wider community what we discover about how the universe works. A big part of it is to bring the scientific way of looking at the world, the approach to thinking about the world that scientists have. We can't think our way into the truth. We need to think of all possible truths and then go out and look at the universe and figure out which ones are right by a very empirical, hypothesis testing, trial and error kind of procedure. Thinking like a scientist, understanding what your own cognitive biases are, testing your ideas against data, these are all things that everyone should have as part of their cognitive tool kit. We as scientists should work harder to actually answer the questions that people have. I'm going to be participating in a debate in May about ‘Is there life after death?' We don't know for sure whether there's life after death, but it would violate everything we know about the laws of physics if it were true. I think that's a piece of evidence against it. If that's right, if there is no life after death, then it has enormous consequences for how we live our lives here on earth. I would like to spread that message as much as possible and have the scientific perspective on our world be just as much a part of the wider cultural discussion as economics or politics or literature.

What do the laws of physics say about life after death?

We think life is not energy but a process. It's a chemical reaction in the crudest terms. It's like the world's coolest chemical reaction because living organisms are extremely complex and highly interconnected networks, and we don't claim to understand it at a deep level. The question is not ‘Where does the energy go at death?' It's ‘What happens to that process?' So dying is like snuffing out a candle. You don't ask ‘Where did the flame go?' The flame is an outcome of this chemical reaction going on in the candle. The flame doesn't go anywhere. It just ceases to be brought into existence by the process. When you see something or somebody die, something changes. What science has brought to the table is that what changes is not that something has left them, but the processes that are going on inside them have changed.

Does studying the universe make human beings seem insignificant?

We're a very tiny, not very significant part of the universe. And this is a blow to our self-image. People don't like to hear that we're not the center of the universe. I like to turn it around. It's true that most of the universe doesn't care about us. We live in a galaxy with 100 billion stars and a universe with 100 billion galaxies, but we're the interesting part of the universe. We are the part of the universe that can think, feel and do things. The significance of us is not given to us by the universe; it's something we need to create for ourselves.